1. Field of the Invention
The present invention relates to a pain abatement catheter system (“PACS”) to be used in treatment and diagnosis within the epidural space of a patient. More specifically, the invention relates to a system of components including a percutaneous introducer assembly, an epidural catheter and an epidural guidewire assembly capable of being steered within the epidural space.
Together, these components define a pain abatement catheter system, PACS, which minimizes procedure time, reduces risk of injury and complications to the patient, provides for greater patient comfort, simplifies use by the practitioner and lessens practitioner exposure to radiation. The three principal components of the present invention, PACS, are discussed in seriatim.
2. Description of the Prior Art
Past problems in Placement or Introducing a Catheter Percutaneously The treatment of intractable nerve pain has traditionally necessitated the percutaneous introduction of large gauge (15–16 g RK) needles into the epidural space whereby the catheter is inserted through the lumen of the needle and into the epidural space. An inherent problem of inserting a catheter into the epidural space in such manner is the risk of catheter shearing due to the piercing tip of the epidural needle. Moreover, advances in the treatment of specific nerve root sleeves require the catheter, once introduced into the epidural cavity, to be advanced and retracted which increases the risk of catheter shearing during the procedure and thereby exposes the patient to unnecessary surgery.
Implantable lead stimulators for the brain and spinal cord have been used for some time in the treatment of chronic pain, spinal cord injury, multiple sclerosis, cerebral palsy, and many other neurological disorders. In addition, spinal cord stimulation has been proposed to promote recovery from injury, to accelerate nerve regeneration, and to induce locomotion. At present, such neural stimulation electrodes and leads are introduced usually for the purpose of pain relief through an epidural needle in the traditional manner and placed into the epidural space in specific locations. The epidural needle is used to introduce, steer, and manipulate these devices within the epidural space. In the present state of the art whereby manipulation of catheters and devices takes place within the lumen of the epidural needle, device damage often results in shearing which can lead to serious patient injury.
Prior Art Catheters and Problems with their Percutaneous Introduction
The Racz Tun-L-Kath of Racz Tun-L-XL catheters by EPIMED are the current standard for use in lysis of epidural adhesions (epidural neuroplasty) and in catheter placement in patients presenting scar tissue or other difficult placements. Many problems and risks are associated with the Racz catheter. For instance, the Racz catheter is caused to “dwell” in the epidural space through a tubular needle which carries a significant risk of catheter damage due to the piercing tip of the epidural needle. In fact, the manufacturer states “DO NOT RETRACT OR REMOVE CATHETER WITH NEEDLE IN PLACE”; however, this is frequently done in practice due to the need to steer the catheter.
The difficult-to-use multi-piece Racz design consists of a 24″ epidural catheter with a stainless steel spring coil end, a detached luer fitting hub, and a stainless steel inner stylet. Its use requires multiple steps: To inject contrast dye or medications, the inner stylet must first be removed and the luer fitting hub correctly placed on the catheter, which is time consuming and cumbersome. After the medications or dyes have been administered, the hub must be removed and the inner stylet replaced to advance the catheter within the epidural space. Each of these steps increases the risk of complications and patient in jury. The spring coil end, in particular, has a dual risk of breakage and of being pierced by the inner stylet which can result in serious damage to the epidural lining, nerve roots, spinal cord, or an unnecessary surgical procedure for the patient.
Risks to the Practitioner Using Prior Art Catheters
The Razz 24″ catheter length places the practitioner extremely close to the radiation source, and does not provide enough distance for a radiation protection lead barrier. The short catheter length necessitates the practitioner's hands to be within inches of the radiation beam, and at times directly in the field of radiation. The effects of low dose fluoroscopic radiation are relatively unknown, although it is known to damage delicate organs such as the eyes and thyroid. Therefore, it is extremely important to follow the three cardinal rules of radiation protection: time, distance, and shielding. Time of exposure should be minimized; distance from the radiation source should be maximized; and a barrier lead shield should be placed between the radiation source and the practitioner. Because radiation is heavier than the atmosphere, a small increase in distance, even inches, makes a vast difference in the amount of scattered radiation received. In fact, when distance from the radiation source is doubled, the amount of scatter radiation is reduced by fifty percent.
Prior Art Guiding Devices
Traditionally, epidural catheters such as the Racz epidural catheter manufactured by EPIMED and presently in use for lysis of epidural adhesions have employed an inner stylet to aid in control and to make the catheter stiffer during insertion and placement. The inner stylet would then be removed and discarded as it was no longer needed. A vexing problem with such practice is that prior to injecting medication or contrast dye into the epidural space the inner stylet must be removed. Likewise, advancement of the catheter requires the inner stylet to be replaced. Such frequent manipulation of the inner stylet during interventional pain procedures is problematic. Inner stylet “freezing” is a frequent occurrence causing the catheter and inner stylet to be forcibly pushed or pulled resulting in the risk of patient injury. In these instances, the catheter must be discarded and a new one introduced percutaneously necessitating removal of the old catheter through the lumen of the needle.